Germ cells are reproductive cells in multicellular organisms. Each mature germ cell is haploid, i.e. it has a single set of chromosomes containing half the usual amount of DNA.
The egg cell (or ovum, or oocyte) is the largest human cell whereas sperm cells are the smallest human cells.
The egg cell consists of a large amount of cytoplasm in which the nucleus is not clearly visible. The sperm contains a nucleus with a small amount of cytoplasm, some mitochondria and a long tail.
The ovum is externally not active. After release, the ovum is passively moved by the fluid-flow in the oviduct (uterine tube), while the sperm cells are active, using their tails to swim against the stream of fluid in the oviduct. They are externally active and mobile.
An egg cell is a metabolically active cell; substances are absorbed and released. Sperm cells are metabolically passive and do not absorb or release substances.
An egg cell lives only 12 to 24 hours in her own environment and cannot be preserved. The egg cell can easily be destroyed. Sperms live about 3 to 5 days in the womb and can be preserved and frozen at temperatures below 60 °C. They are not easy to destroy.
For a conception one ovum and millions of sperm are required.
The egg cell develops in one of the two ovaries in the warm abdominal cavity, the sperm develop in the testicles just outside the body in a relatively cold environment.
Egg cells are produced well before birth in a huge number. They mature from puberty to menopause. The first sperm cells are formed only from puberty. Then the sperm production goes on and never stops.